Exotic mesons with hidden bottom near thresholds

Abstract

We study heavy hadron spectroscopy near open bottom thresholds. We employ $\mathrm{B}$ and ${\mathrm{B}}^{*}$ mesons as effective degrees of freedom near the thresholds, and consider meson exchange potentials between them. All possible composite states which can be constructed from the $\mathrm{B}$ and ${\mathrm{B}}^{*}$ mesons are studied up to the total angular momentum $J\ensuremath{\le}2$. We consider, as exotic states, isosinglet states with exotic ${J}^{PC}$ quantum numbers and isotriplet states. We solve numerically the Schr\"odinger equation with channel couplings for each state. The masses of twin resonances ${\mathrm{Z}}_{\mathrm{b}}(10\text{ }610)$ and ${\mathrm{Z}}_{\mathrm{b}}(10\text{ }650)$ recently found by Belle are reproduced. We predict several possible bound and/or resonant states in other channels for future experiments.